發(fā)布時(shí)間：2018-01-29 16:53

  本文關(guān)鍵詞： 川西北 卡尼期氣候事件 沉積微相 環(huán)境演化 硅質(zhì)海綿礁　出處：《成都理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：晚三疊世卡尼期氣候事件是三疊紀(jì)最顯著的全球氣候變化事件之一,在川西北綿竹漢旺、綿竹觀音崖、安縣雎水等地馬鞍塘組中也被等時(shí)識(shí)別,主要反映了從碳酸鹽巖到碎屑巖的巖性變化。在晚三疊世末期的印支運(yùn)動(dòng)效應(yīng)下,加之晚三疊世極為動(dòng)蕩的古氣候特征,使得川西北馬鞍塘組沉積環(huán)境極為復(fù)雜,沉積相劃分存在爭(zhēng)議。本次研究的目標(biāo)是厘定川西北卡尼期氣候事件沉積的微相特征,探究卡尼期氣候事件前后的沉積環(huán)境演化過(guò)程和規(guī)律,及其在古生物學(xué)、地球化學(xué)等方面的響應(yīng)。通過(guò)野外剖面勘察、采樣及室內(nèi)薄片分析,古生物化石鑒定,地化測(cè)試手段,結(jié)合國(guó)內(nèi)外卡尼期事件的研究資料及采取巖石沉積微相恢復(fù)古環(huán)境的方法,對(duì)卡尼期地層剖面中碳酸鹽巖至陸源碎屑巖段的巖相學(xué)、古生物學(xué)、地球化學(xué)特征進(jìn)行分析。發(fā)現(xiàn)川西北馬鞍塘組沉積序列從早卡尼期的生屑—鮞粒灰?guī)r和早卡尼期末發(fā)育的硅質(zhì)海綿礁灰?guī)r,突變?yōu)橹锌崞诤谏珪?shū)頁(yè)狀頁(yè)巖,最后至晚卡尼期鈣質(zhì)粉砂質(zhì)泥巖、鈣質(zhì)泥質(zhì)粉砂巖。將馬鞍塘組碳酸鹽段劃分為6個(gè)微相類型和17個(gè)次級(jí)微相微相類型,將碎屑巖段劃分為5個(gè)微相類型,認(rèn)為研究區(qū)晚三疊世卡尼期環(huán)境演化過(guò)程從內(nèi)緩坡鮞�！紴﹣喯唷芯徠迈b粒-生屑灘亞相→中緩坡硅質(zhì)海綿礁亞相→淺海泥亞相→濱海潮坪亞相,最后到小塘子組三角洲前緣亞相的變化。淺海泥亞相的灰黑色鈣質(zhì)泥頁(yè)巖中生物多見(jiàn),植物葉片和莖桿化石、黃鐵礦豐富,顯示著低能貧氧的環(huán)境又伴隨著淡水輸入的過(guò)程,這一明顯的巖相變化與卡尼期氣候事件過(guò)程中淡水和陸源碎屑物質(zhì)大量輸入有重要的關(guān)系。推測(cè)地層序列中碳酸鹽補(bǔ)償深度(CCD)上升,同時(shí)依據(jù)C、O同位素偏移以及卡尼期菊石標(biāo)志性分子等特征認(rèn)為研究區(qū)卡尼期事件沉積與西特提斯洋地區(qū)卡尼期氣候事件具有等時(shí)對(duì)比性,馬鞍塘組中部硅質(zhì)海綿礁的死亡則可能受海平面升降速率、大火山巖省集中爆發(fā)、板塊構(gòu)造運(yùn)動(dòng)和季風(fēng)性氣候等因素的影響。這一系列地質(zhì)現(xiàn)象與晚三疊世古氣候復(fù)雜多變、海平面升降變化頻繁、構(gòu)造活躍有重大關(guān)系。
[Abstract]:The late Triassic Carney climate event is one of the most significant global climate change events in Triassic. It is also identified in Maantang formation of Mianzhu Hanwang, Mianzhu Guanyin Cliff, Anxian Jushui in northwestern Sichuan. It mainly reflects the lithologic changes from carbonate rocks to clastic rocks. Under the Indosinian movement effect at the end of the late Triassic and the extremely turbulent paleoclimate of the late Triassic. The sedimentary environment of Maantang formation in northwestern Sichuan is very complex and the sedimentary facies division is controversial. The purpose of this study is to determine the microfacies characteristics of the Kani climatic events in northwestern Sichuan. The evolution process of sedimentary environment and its response in paleontology and geochemistry before and after the Carney climatic events were studied. The fossil fossils were identified by field profile survey sampling and laboratory sheet analysis. Combined with the research data of Carney events at home and abroad and the method of recovering paleoenvironment by sedimentary microfacies, the lithofacies and paleontology of carbonate rock to continental clastic rock in Carney stratigraphic profile were studied. It is found that the sedimentary sequence of Maantang formation in northwestern Sichuan changed from early Carney bioclastic oolitic limestone and siliceous sponge reef limestone to middle Carney black sheet shale. Finally, calcareous silty mudstone and calcareous argillaceous siltstone are divided into 6 microfacies types and 17 secondary microfacies types, and the clastic rock member is divided into 5 microfacies types. It is considered that the environmental evolution process of the late Triassic Carney period in the study area changed from the inner gentle slope to the subfacies of the oolitic shoal. 鈫扢iddle gentle slope oolitic shoal subfacies. 鈫扢iddle gentle slope siliceous sponge reef subfacies. 鈫扴hallow-sea mud subfacies. 鈫扵he subfacies of littoral tidal flat and finally to the delta front subfacies of Xiaotangzi formation. There are many organisms in the gray black calcareous shale of the shallow-sea mud subfacies and the fossil plant leaves and stems are rich in pyrite. It shows that the environment of low energy and poor oxygen is accompanied by the process of fresh water input. This obvious lithofacies change has an important relationship with the mass input of fresh water and continental clastic materials during the Carney climatic event. The carbonate compensation depth (CCDD) in the stratigraphic sequence is estimated to be rising, and at the same time, according to C. The characteristics of O isotope migration and the signature molecules of Carney permethrin suggest that the Carney event deposition in the study area is isochronous to the Carney climatic events in the West Tethys Ocean. The death of siliceous spongy reef in the middle of Maantang formation may be affected by the rate of sea level rise and rise. This series of geological phenomena is closely related to the late Triassic paleoclimate, the frequent changes of sea level and the active tectonics.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P532;P534.51

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